Inducing Electron Dissipation of Pyridinic N Enabled by Single Ni–N4 Sites for the Reduction of Aldehydes/Ketones with Ethanol

Transfer hydrogenation (TH) of aldehydes/ketones with renewable and nontoxic ethanol is an attractive solution to produce alcohols. Here, we found that single-atom Ni–N4 site catalysts bring high activity and selectivity for the reduction of hydroxymethyl-functionalized aldehydes/ketones using renewable and nontoxic ethanol as the hydrogen source. When biomass-derived 5-hydroxymethylfurfural was used as the substrate, a turnover frequency (TOF) value of 22 h–1 for the as-prepared catalyst was achieved. Experiments and simulating computation revealed that pyridinic N of the Ni–N4 site is the active center and the presence of single-atom Ni reduces the electron density of its coordinated pyridinic N and thus achieves the high catalytic activity, demonstrating the possibility of catalytic TH reactions over metal-free sites.